Update vendor (slack)

vendor/github.com/nlopes/slack/conversation.go

@@ -0,0 +1,37 @@
+package slack
+
+// Conversation is the foundation for IM and BaseGroupConversation
+type conversation struct {
+	ID                 string   `json:"id"`
+	Created            JSONTime `json:"created"`
+	IsOpen             bool     `json:"is_open"`
+	LastRead           string   `json:"last_read,omitempty"`
+	Latest             *Message `json:"latest,omitempty"`
+	UnreadCount        int      `json:"unread_count,omitempty"`
+	UnreadCountDisplay int      `json:"unread_count_display,omitempty"`
+}
+
+// GroupConversation is the foundation for Group and Channel
+type groupConversation struct {
+	conversation
+	Name       string   `json:"name"`
+	Creator    string   `json:"creator"`
+	IsArchived bool     `json:"is_archived"`
+	Members    []string `json:"members"`
+	Topic      Topic    `json:"topic"`
+	Purpose    Purpose  `json:"purpose"`
+}
+
+// Topic contains information about the topic
+type Topic struct {
+	Value   string   `json:"value"`
+	Creator string   `json:"creator"`
+	LastSet JSONTime `json:"last_set"`
+}
+
+// Purpose contains information about the purpose
+type Purpose struct {
+	Value   string   `json:"value"`
+	Creator string   `json:"creator"`
+	LastSet JSONTime `json:"last_set"`
+}